The structure of a digital lock has been repeatedly improved but such a lock can be opened by a thief who can overcome its mechanical characteristics. For example, by means of a difference in precision of lock rings, one can rotate lock rings one by one and find the exact number for opening the lock. Some locks may be opened by holding or rotating the handle and finding the exact position of lock rings through shaking or by finding a defect in their mechanical structure.
From an analysis the inventor has found that an ordinary digital lock has a projection on its locking piece which is vibrated during a small movement.
The inventor, considering such a defect and with careful research, has designed a floating locking piece without projections for making a reliable digital lock.